Lizards trapped in amber for 100 million years may be some of the oldest of their kind

Tree resin can be bad news for a tiny animal: The sticky tree sap can stop small creatures in their tracks, freezing them forever in time. But that's good news for scientists. If you've ever seen "Jurassic Park," you have some idea of how great tree resin is at preserving finicky soft tissues. The hardened amber can keep specimens remarkably intact for millions of years.

Now, scientists have examined a flight of lizards locked away in the stuff about 100 million years ago. Among the specimens is a tiny young lizard that could be the oldest chameleon ever found — a staggering 78 million years older than the previous record breaker. One of the geckos may be the most complete fossil of its kind and age. These and 10 other fossilized lizards are described in a paper published Friday in Science Advances.

A scan from one of the lizards. (Juan Daza et al.; Science Advances)

Study co-author Edward Stanley, a University of Florida postdoctoral student in herpetology at the Florida Museum of Natural History, encountered the fossils at the American Museum of Natural History, in New York. They'd been made available for study by a private collector and had been dated back about 100 million years, based on the Burmese mine they'd been found in. But even though the fossils had been uncovered for a while, Stanley and his colleagues were the first to determine how special they were by using 3-D scanning techniques to reconstruct the creatures within.

A micro-CT scan of the ancient gecko. (University of Florida)

During the middle Cretaceous Period, when these lizards lived, much larger reptiles also roamed the Earth. It wasn't quite the heyday of the dinosaurs yet, but a few bruisers like the Carnotaurushad already hit the scene. But as their hulking cousins took over the food chain, little lizards like the ones found in these fossils were just starting to diversify — branching off into families that would evolve into modern reptiles. Because they were so tiny and delicate (some of them less than an inch long) many of these important evolutionary players have been lost to decay.

“The fossil record is sparse because the delicate skin and fragile bones of small lizards do not usually preserve, especially in the tropics, which makes the new amber fossils an incredibly rare and unique window into a critical period of diversification," Stanley said in a statement.

More analysis is needed to determine whether the creature really had this feature — and whether it can be placed in the same branch of the lizard family tree as a modern chameleon. The researchers involved say they will classify the new species in a future paper.

Even if the "chameleon" is something else and loses its superlative title, the dozen specimens provide a rare look into the diversification of lizards.

Correction: This article has been updated to clarify that the specimens have been made available for study by their owner, which does not necessarily mean they have been donated.

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